1. Field of the Invention
The present invention relates to devices for stretching, such as an artist""s canvas. More particularly, the invention comprises a system for stretching canvas, or other material, tautly while ensuring that the frame retains a true rectangular shape.
2. Description of the Prior Art
Stretching frames are used for a variety of purposes, including the stretching of artists"" canvas or other materials. Rigidity and the ability to expand the outer perimeter of the frame are both important elements for maintaining tautness in the stretched canvas, especially as the size of the frame increases. A number of different approaches have been taken to ensure that these factors are met, including:
U.S. Pat. No. 5,271,171, issued to David C. Smith on Dec. 21, 1993, presents a COMPRESSIBLE AND EXPANDABLE STRETCHING FRAME WITH ADJUSTABLE CORNER BRACKETS, wherein opposite pairs of hollow, open ended tubes are joined by corner brackets slidably inserted into the open ends of the tubes, thereby form a rectangular frame. A groove formed into each of the four tubes creates a channel around the interior perimeter of the rectangular frame for receiving an edge of a silk screen fabric which is held, under tension by a locking rod. A tensioner, consisting of a compressible spring and within an internally threaded hole and an externally threaded nut, incorporated in each leg of the corner brackets provides adjustable tension to the silk screen fabric. The present invention requires only eight interlocking wooden members, making it less costly and, due to the unique interlocking method, more rigid, and, due to its simplicity, components of various sizes may be combined to construct a multitude of frame sizes.
U.S. Pat. No. 5,052,462, issued to John Stobart on Oct. 1, 1991, presents a CANVAS TENSIONING PICTURE FRAME, wherein the four members forming the sides of the rectangular frame are each cut at a 45xc2x0 angle. Each angled end has two half round cavities cut therein with a tapered half bore from one cavity to the other, such that when two members are joined the cavities form two full round cavities joined by a tapered bore, the upper cavity having an opening of lesser diameter open to the surface of the frame. An disk having a lip around its perimeter occupies the upper cavity, extending through the, while a disk having a bored center occupies the lower cavity. Fitted into a square aperture at the center of the upper disk is a square headed, frustoconical screw which engages the tapered bore between the upper and lower cavities. A clockwise rotation of this screw forces the two abutting members of the frame apart, thus forcing a stretching of the canvas, allowing periodic tightening of a slackened canvas. Again, the present invention requires only eight interlocking wooden members, making it less costly and, due to the unique interlocking method, more rigid, and, due to its simplicity, a multitude of frame sizes can be produced with only a small investment in pairs of opposite members.
U.S. Pat. No. 4,635,700, issued to Gustav A. Berger on Jan. 13, 1987, presents a SELF-ADJUSTING CANVAS TENSIONING FRAME, wherein a canvas is stretched over a rigid frame with constant tension being maintained on the canvas by a series of adjustable springs. The canvas is rigidly attached to a first side of the frame by tacks. The two adjacent sides of the canvas are wrapped around the rigid frame and secured by tensioning springs mounted through the canvas at grommets. The fourth edge of the frame consists of an outer frame member fastened to the frame by bolts passing through coil springs under compression such that the outer frame member is disposed to being force outward from the inner frame. The fourth edge of the canvas is rigidly attached to this outer frame member by tacks while the end of the two adjacent sides are attached to the outer frame member by tensioning springs as the rest of their length has been attached to the rigid frame. Constant tension is thereby maintained on the canvas. Once again, the present invention requires only eight interlocking wooden members, making it less costly and, due to the unique interlocking method, more rigid, and, due to its simplicity, a variety of different frame sizes can made by simply using various pairs of opposite members.
U.S. Pat. No. 4,432,150, issued to Russell A. Swonger on Feb. 21, 1984, presents a STRETCHER FRAME FOR AN ARTISTS CANVAS, wherein the four members forming the sides of the rectangular frame are each compound mitered at a 45xc2x0 angle such that a canvas may be mounted with only the extreme edge in contact with the frame. A dovetail channel is cut diagonally across the corners such that joined side members are held in place by a complementary dovetail key. With a canvas mounted to the frame, tension can be adjusted by inserting wedges into the joints between adjacent side members. Due to its unique interlocking method, the present invention provides a more rigid frame.
U.S. Pat. No. 3,494,409, issued to Robert A. Prechtl, et. al., on Feb. 10, 1970, presents a COLLAPSIBLE STRETCH FRAME AND CANVAS, wherein the four members forming the sides of the rectangular frame are each mitered at a 45xc2x0 angle and one face of each is dadoed such that a canvas may be mounted with only the extreme edge in contact with the frame. The inside corners of adjacent side members are mortised to receive a wedge for securing the adjacent sides. The canvas is rigidly secured to two opposite sides by staples or tacks and to the remaining two sides by retaining devices forcing the canvas into a groove cut into the outer surface of the members. Prechtl does not make any specific provision for re-tensioning the canvas after it has been mounted to the frame, but rather allows for ease of assembly and disassembly of the frame, even after the canvas has been mounted. Due to its unique interlocking method, the present invention provides a more rigid frame.
U.S. Pat. No. 1,847,925, issued to Robert A. Carter on Mar. 1, 1932, presents a STRETCHER, wherein the four members forming the sides of the rectangular frame are each mitered at a 45xc2x0 angle, with each corner having both a square mortise and corresponding square tenon. With such a mortise and tenon arrangement, the mortise of one side member engages the tenon of the second while the mortise of the second member engages the tenon of the first. With such a configuration, either one or two wedges can be driven into each corner of the frame to cause expansion of the joint in either or both of the two directions. Due to its unique interlocking method, the present invention provides a more rigid frame.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
Stretching frames are used for a variety of purposes, including the stretching of artists"" canvas or other materials. Rigidity and the ability to expand the outer perimeter of the frame are both important elements for maintaining tautness in the stretched canvas, especially as the size of the frame increases. The present invention, through its unique interlocking member system, offers a means to overcome these problems.
Accordingly, it is a principal object of the invention to provide a stretching frame which is economical.
It is another object of the invention to provide a stretching frame which provides a high degree of rigidity.
It is a further object of the invention to provide a stretching frame with which it is easy to adjust tension on the installed canvas.
Still another object of the invention is to provide a stretching frame which can be erected in a variety of different sizes with a minimal investment in materials.
An additional object of the invention is to provide a stretching frame which can be produced from a variety of different materials.
It is again an object of the invention to provide a stretching frame which is easily disassembled and stored or transported.
Yet another object of the invention is to provide a stretching frame which is resistant to warping or deformation in any direction.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.